Question

the wavelengths of ultraviolet waves are tiny, so scientists sometimes measure them in nanometers (nm) instead of meters (1 nm = 0.000000001 m). we divide uv waves in three main groups, each with a different range of wavelengths: uva, uvb, and uvc. this model shows the range of wavelengths for each of these groups. 400 nm 315 nm 280 nm 100 nm uva uvb uvc select the true statements. an electromagnetic wave with a wavelength of 290 nm is a uvb wave. uvc waves have lower energies than uva and uvb waves. uva waves have lower frequencies than uvb and uvc waves.

Explanation:

1. From the given wavelength ranges, UVB ranges from 280 - 315 nm. So, a 290 - nm wave is UVB.
2. Energy of an electromagnetic wave is inversely proportional to wavelength ($E=\frac{hc}{\lambda}$). UVC has shorter wavelengths than UVA and UVB, so it has higher energy. The statement "UVC waves have lower energies than UVA and UVB waves" is false.
3. Frequency ($

u$) and wavelength ($\lambda$) are related by $c = \lambda
u$ (where $c$ is the speed of light). UVA has longer wavelengths than UVB and UVC, so it has lower frequencies.

Answer:

An electromagnetic wave with a wavelength of 290 nm is a UVB wave.
UVA waves have lower frequencies than UVB and UVC waves.